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MEAT SCIENCE AND MUSCLE BIOLOGY |
* Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506-0201;
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Department of Statistics, Kansas State University, Manhattan 66506;
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Department of Animal Science, Oklahoma State University, Stillwater 74078;
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Department of Animal Science, Texas Tech University, Lubbock 79409;
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# Department of Animal Science, University of Illinois, Champaign 61801;
and
|| Consultant, 1525 E. Kay Street, Derby, KS 63037; and
¶ Intervet/Schering-Plough Animal Health, DeSoto, KS 66018
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Abstract |
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 Top Abstract INTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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Key Words: β-adrenergic agonist • beef • display color • high oxygen and carbon monoxide modified atmosphere packaging • overwrap packaging • zilpaterol hydrochloride
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INTRODUCTION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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; John et al., 2005; Mancini and Hunt, 2005). A polyvinyl chloride (PVC) overwrap results in a desirable red color expected of fresh beef but has a short retail color life (Kropf, 2004). Benefits of modified atmosphere packaging (MAP) include extended color life (Sørheim et al., 1999; Jayasingh et al., 2001; Seyfert et al., 2004; Eilert, 2005). High-oxygen MAP (HO-MAP) uses 4 times as much oxygen in the atmosphere, which delays formation of metmyoglobin (Jeyamkondan et al., 2000), thereby extending the color life, but hastened onset of lipid oxidation (Jeyamkondan et al., 2000; John et al., 2005) is a disadvantage. However, antioxidants, such as rosemary, slow this oxidation (Mancini et al., 2005). Carbon monoxide MAP (CO-MAP) includes benefits of a more stable red color, longer shelf life, and improved flavor due to less lipid oxidation (Jayasingh et al., 2001; Kropf, 2004; Eilert, 2005; Cornforth and Hunt, 2008) because of the inherent no or ultra-low oxygen in this system.
Beta-adrenergic agonists fed to cattle and swine increased HCW and lean tissue development, improved feed efficiencies, and reduced fat deposition (Beermann, 2004; Dikeman, 2007; Quinn et al., 2008). Zilpaterol hydrochloride (ZH, a β agonist) gained US approval in 2006 (FDA 2006). Cattle fed ZH for 30 or 50 d extended the display color life of LM steaks (Strydom et al., 2000). Avendaño-Reyes et al. (2006) reported similar tissue lightness for cattle fed ZH, ractopamine, or no β-agonist on d 1 and 14; however, d-5 control steaks were less dark (P < 0.05) than steaks from either β-agonist treatment.
Few studies have analyzed the effects of feeding ZH on color development and stability of muscles from supplemented cattle. Our study evaluated initial color, color stability, and instrumental color of crossbred beef semimembranosus (SM) steaks from beef cattle fed ZH and packaged with PVC and in HO-MAP and CO-MAP.
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MATERIALS AND METHODS |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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Animal Selection and Raw Materials
More than 1,073 head of crossbred beef steers (all Bos taurus) were fed at a commercial feed yard in Texas. Steers were allotted randomly to 4 dietary regimens and fed a typical feedlot finishing diet supplemented without or with 7.56 g/t of ZH (100% DM basis, Intervet/Schering-Plough Animal Health, DeSoto, KS) for 0, 20, 30 or 40 d before slaughter (ZH0, ZH20, ZH30, and ZH40, respectively). Cattle were implanted on d 0 (arrival at feedlot) and again on d 80 with a Revalor-IS (80 mg of trenbolone acetate and 16 mg of estradiol, Intervet/Schering-Plough).
All cattle were removed from ZH supplementation 3 d before slaughter at a federally inspected commercial facility in Texas in late January 2007. Carcasses were electrically stimulated (45 V) 30 min postmortem and chilled at 0 ± 2°C in a bone-to-bone configuration. Carcasses (n = 60, HCW of 324 to 439 kg, rib eye area of 77.4 to 116 cm2, USDA slight marbling, and USDA A-maturity) were selected randomly on d 1 postmortem, and 15 inside rounds (NAMP # 168; NAMP, 2007) from each feeding duration (ZH0, ZH20, ZH30, or ZH40) were removed from one side of each carcass, vacuum packaged, and commercially shipped (14 to 18 h) refrigerated (1 to 3°C) to the Kansas State University Meat Laboratory.
Subprimal Processing
On d 9 postmortem, the vacuum-packaged, whole muscle weight of all subprimals was recorded. Cuts were unpackaged and drained, and a blotted weight was taken. The percentage purge loss of each muscle was calculated. Subprimals (n = 60 total, 15 from each feeding group) were trimmed to remove the adductor muscle and excess fat, leaving the SM. Muscles were then reweighed to determine the percentage SM subprimal yield. A 7.62-cm-thick anterior portion of each SM was removed, re-vacuum packaged (barrier bag 620, Cryovac Sealed Air Corp., Duncan, SC), and placed into dark storage at 2°C until d 21 postmortem to simulate pre-retail storage before cutting and display in aerobic packaging. The remaining SM portion was vacuum packaged and placed into dark storage at 2°C until d 10 postmortem when it was enhanced and fabricated into steaks for MAP.
Enhancement and Steak Fabrication
On d 10, the larger SM portion was removed from the package and weighed. Fifteen sets of 4 randomly selected muscles (1 from each feeding group per set) were passed once through a multiple-needle injector (Model N30, Wolftec Inc., Werther, Germany). Each SM was injected (10% pump) with a solution resulting in meat containing 0.3% sodium chloride, 0.35% phosphate (BRIFISOL 85 Instant, BK Giulini Corp., Simi Valley, CA), and 0.05% rosemary extract (NatureGuard Rosemary Extract, Newly Weds Foods Co./NORAC, Edmonton, Alberta, CA). After a 10-min post-pump drain period, each SM was reweighed to determine the actual percentage pump calculated as [(pumped and drained cut wt. – unpumped cut wt.) ÷ unpumped cut wt.] x 100. The SM was faced and fabricated into five 2.54-cm-thick steaks. Three steaks were assigned randomly to a HO-MAP system (80% O2, 20% CO2) for 0, 3, or 5 d of retail display. The remaining 2 steaks were allotted to a CO-MAP system (69.6% N2, 30% CO2, and 0.4% CO) for 0 or 9 d of retail display. All MAP steaks were placed with the fresh-cut surface up in 24.5 cm x 14.3 cm x 5.0 cm rigid polypropylene trays (CS1178, Cryovac Sealed Air Corp.) containing tray diapers (Dri-Loc Soaker Pads, AC-50, Cryovac Sealed Air Corp.), covered with oxygen-barrier film (Lid 550, 1.0 mils; less than 20.0 oxygen transmission mL/24 h/m2 at 4.4°C with 100% relative humidity (RH) and moisture vapor transmission less than 0.1 g/24 h/645.2 cm2 at 4.4°C and 100% RH, Cryovac Sealed Air Corp.), and packaged (Ross Jr. S-3180, Ross, Midland, VA). The HO-MAP and CO-MAP packages were boxed and placed into dark storage for 4 and 11 d, respectively, before being put into simulated retail display at postmortem d 14 and 21, respectively. Two activated oxygen scavengers (ActiveTech, Pactiv, Chicago, IL) were included in each CO-MAP package to eliminate residual O2 during storage and display.
At d 21 postmortem, the unenhanced SM portion was unpackaged, faced, and two 2.54-cm-thick steaks were cut and placed cut surface up on 2S or 4S foam trays (Cryovac Sealed Air Corp.) containing tray diapers. Steaks were overwrapped with a PVC oxygen-permeable film (MAPAC-M film, 23,250 mL/m2/24 h, 72 gauge, Resinite Packaging Films, Borden Inc., North Andover, MA), and assigned to 0 or 3 d of retail display. On d 21 postmortem unenhanced steaks were placed into simulated retail display upon completion of fabrication and PVC packaging. Commercial product destined for enhancement and HO-MAP is often processed relatively early postmortem (as per our 10 d processing and d 14 for start of display) because this packaging method has a shorter shelf life and is more subject to lipid oxidation than a product in vacuum or CO-MAP. Product is often stored longer in vacuum before cutting retail cuts for PVC overwrapping or before processing into a no-oxygen MAP containing CO (as per our 21-d aging time before initial display).
pH
The pH was measured on d 0, 3, and 5 or d 0 and 9 for HO-MAP or CO-MAP packaged steaks, respectively, by inserting the tip of a previously calibrated probe (MPI pH probe, glass electrode, Meat Probes Inc., Topeka, KS) twice into the deep SM (DSM) and 3 times into the superficial SM (SSM). Using the same technique, PVC steak pH was measured on d 0 and 3. Measurements were averaged, and a final value was calculated for the DSM and SSM portions of each steak.
Retail Display
Steaks were displayed under continual fluorescent lighting (2,153 lx, 3,000°K, CRI = 85, Bulb model F32T8/ADV830/Alto, Philips, Bloomfield, NJ) at 2 ± 1.3°C in open-topped cases (Unit model DMF8, Tyler Refrigeration Corp., Niles, MI) for up to 9 d depending on the package system. Display cases were completely filled with one layer of packages that were rotated daily to minimize variation due to package location in the case. Cases automatically defrosted every 12 h, and case temperature was monitored during display using temperature loggers (RD-TEMP-XT, Omega Engineering Inc., Stamford, CT).
Visual Color
Trained color panelists (n = 6 to 8) who had passed the Farnsworth-Munsell 100-hue test (Macbeth, Newsburgh, NY) evaluated the SSM (the outer 1/3 of the SM, which typically chills faster and is darker) and the DSM (the inner 1/3 of the SM, which chills slower and is often more pale) for initial color, display color, and discoloration (AMSA, 1991). On d 0 of display, initial color evaluations were made, whereas display color and discoloration scores were recorded daily for PVC steaks on 0 through 3 d of simulated display.
Steaks packaged in HO-MAP and CO-MAP were in simulated retail display for 5 and 9 d, respectively. The initial color scale used across packaging treatments was 1 = purplish pink or red or reddish tan of vacuum packages; 2 = bleached, pale red; 3 = slightly cherry red; 4 = moderately light cherry red; 5 = cherry red; 6 = slightly dark red; 7 = moderately dark red; 8 = dark red; and 9 = very dark red. Panelists scored each region to half-point increments.
The display color scale for evaluating color stability, also rated to the nearest half-point, was 1 = very bright red or very bright pinkish red; 2 = bright red or bright pinkish red; 3 = dull red or dull pinkish red; 4 = slightly dark red or slightly dark pinkish red; 5 = moderately dark red or moderately dark pinkish red; 6 = dark red to dark reddish tan or dark pinkish red to dark pinkish tan; 7 = tannish red or tannish pink; and 8 = tan to brown. According to our scale, panelists were instructed that a score of 5.5 indicated borderline acceptability of steaks.
The discoloration scale indicated, to the nearest whole point, the percentage of surface discoloration due to metmyoglobin formation. The scale used was 1 = none (0%); 2 = slight discoloration (1 to 19%); 3 = small discoloration (20 to 39%); 4 = modest discoloration (40 to 59%); 5 = moderate discoloration (60 to 79%); 6 = extensive discoloration (80 to 99%); and 7 = total discoloration (100%). Daily scores from each panelist for initial color, display color, and discoloration were averaged before statistical analysis.
Instrumental Color
By using a calibrated HunterLab MiniScan XE Plus Spectrophotometer (45/0 LAV, 2.54-cm-diam. aperture, 10° standard observer, Illuminant A, Hunter Associates Laboratory Inc., Reston, VA), PVC steaks were evaluated for instrumental color on d 0 and 3, whereas HO-MAP and CO-MAP steaks were evaluated for instrumental color at 0, 3, and 5 d or 0 and 9 d, respectively. The Commission Internationale d’Eclairage L*, a*, and b* values were recorded and used to calculate hue angle (tan–1 b*/a*) and saturation index (a*2+ b*2)1/2. Each steak was scanned twice for the DSM and 3 times for the SSM and averaged within muscle area for statistical analysis.
Odor and Gas Concentration
The MAP were evaluated for CO2, O2, and CO head space gas concentrations (Tri-Gas MAP Headspace Analyzer, model 900121, sampling rate = 5 mL/sec; resolution = CO: 0.001%; CO2: 0.01%; O2: 0.01%; Bridge Analyzers Inc., Alameda, CA) at 0, 3, and 5 d of visual display for HO-MAP and 0 and 9 d for CO-MAP. Odor scores were subjectively measured on d 9 CO-MAP steaks immediately after the packages were opened by 2 individuals familiar with typical off-odors of meat products. The following scale was used: 1 = no off-odor; 2 = slight off-odor; 3 = small off-odor; 4 = moderate off-odor; and 5 = extreme off-odor, with values greater than 3.5 considered unacceptable.
Statistical Analysis and Design
The experimental design was a split plot with the whole plot experimental unit as a beef steer to which feeding treatments were randomly assigned. Individual steaks were the subplot experimental units assigned randomly to day of retail display. Visual and instrumental color traits were repeat measures taken on each muscle area (DSM and SSM). Data across packaging treatments were analyzed separately. Using the MIXED procedure (SAS Institute Inc., Cary, NC), subsets of least squares means were subjected to pairwise comparisons using Fisher’s LSD procedure at the (P < 0.05) level of significance, depending on which main effects and interactions were significant. Diet, muscle area, and day were the main effects tested. Interactions tested were diet x display day, diet x muscle area, muscle area x day, and diet x day x muscle area. When appropriate to simplify mean comparisons we compared means for 1) the 2 display times for each muscle area x diet combination, 2) the 2 muscle areas for each diet x display time combination, and 3) the 4 diets for each display time x muscle area combination.
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RESULTS AND DISCUSSION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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pH.
No differences (P > 0.05) in pH occurred because of ZH feeding duration (Table 1) or display day (data not shown). Our pH values (5.44 to 5.46) were typical of beef muscle and were not likely a factor in any color differences. Avendaño-Reyes et al. (2006) also reported no difference in pH values of LM steaks from beef steers fed ZH, ractopamine, or no β-agonist. The pH values of the DSM (5.47) were greater (P < 0.05) than those from the SSM (5.45). Although significant, differences in pH between the DSM and SSM were not likely large enough to affect meat color chemistry. Lee et al. (2008) also found greater (P < 0.05) pH values for the cranial-dorsal quadrant (corresponding to the DSM). In contrast to our study, Seyfert et al. (2006) found no differences (P > 0.05) in pH values of beef DSM and SSM. Nevertheless, it is well established that the postmortem environment to which the SM is exposed before the onset of ultimate pH can play an important role in pH differences between the DSM and SSM (Sammel et al., 2002a,b, Seyfert et al., 2006).
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and Seyfert et al. (2006) reported a lighter red (P < 0.05) initial color for the DSM than the SSM. The more pale color typical of the DSM (compared with the SSM) can be attributed to high temperatures early postmortem found within the DSM. Seyfert et al. (2006) noted that early postmortem, the DSM had a decreased oxygen consumption rate allowing for a bright red initial color to develop upon exposure to oxygen. Display Color. No diet x display day interaction (P > 0.05) occurred for display color values (Table 1), but as expected, display color deteriorated as display time increased. The diet x muscle area interaction for display color was significant (Figure 1). The DSM portion of steaks had no difference (P > 0.05) in display color scores across ZH treatments; however, the SSM from the ZH20 diet was brighter red (P < 0.05, decreased display color scores) than the SSM from ZH40 fed steers. For steaks from cattle fed ZH0, ZH20, or ZH30, no differences (P > 0.05) in display color scores occurred between the DSM and SSM portions. Only steaks from the ZH40 group had a darker (P < 0.05) SSM portion compared with the DSM. It appears that feeding ZH for an extended period of time (40 d) may cause the differences in display color scores that developed between the DSM and SSM.
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Instrumental Color.
A diet x muscle area x display day interaction occurred for L* values of beef steaks (Table 2). Dietary differences only occurred for the DSM area on d 0 of display. Steaks from cattle fed ZH20 had a lighter (P < 0.05, greater L* value) DSM area on d 0 of retail display than cattle from the ZH40 diet; however, no dietary differences (P > 0.05) in L* values were seen on d 0 for the SSM. By d 3 of display, there were no differences (P > 0.05) in L* values due to diet regimen in the DSM and SSM. Avendaño-Reyes et al. (2006) displayed longissimus steaks from cattle fed ZH, ractopamine, or no β-agonist for 14 d and reported no treatment difference (P > 0.05) in L* values on d 1 or 14; however, control steaks were darker (P < 0.05, reduced L* value) on d 5 than steaks from either β-agonist treatment.
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; Seyfert et al., 2006). The DSM portion of steaks from beef steers fed ZH40 was redder (P < 0.05) than the DSM portion of steaks from other dietary treatments (Table 3). No dietary differences (P > 0.05) in a* values occurred for the SSM portion. In contrast, Avendaño-Reyes et al. (2006) saw a significant difference due to diet treatment; the ZH group had reduced a* values compared with control cattle; however, no differences in feeding duration were tested in their study.
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Overall, steaks on d 0 of display were more yellow, more vivid (greater saturation indices), and had greater hue angle values (P < 0.05) than d-3 steaks. Our saturation index values indicated a shift to a less saturated color over time for the beef SM. Decreased (P < 0.05) saturation index values from d 0 to 3 reflect the loss (P < 0.05) in redness (decreased a* values) and yellowness (decreased b* values) of steaks with increasing day of display. The large decrease in saturation index values coincides with the color change from bright to dark red as seen by display color panelist scores.
Seyfert et al. (2006) and Sawyer et al. (2007) also reported a loss (P < 0.05) in yellowness and vividness (saturation index) from d 0 to 3 of display. Sammel et al. (2002a) also had less (P < 0.05) saturation indices on d 3 than d 0 of display but increased (P < 0.05) d-3 hue angle values compared with d 0. Although the difference in hue angle values across day of display was significant, it is not of much practical importance.
HO-MAP-Packaged Steaks
Percentage Pump and pH.
The average percentage pump for the enhanced SM muscles was 7.5%. No differences (P > 0.05) in pH values occurred for the main effect of diet for beef steer steaks packaged in HO-MAP (Table 4). The pH was slightly greater (P < 0.05) for the DSM (5.75) compared with the SSM (5.67), but this small difference likely had minimal impact on color. Avendaño-Reyes et al. (2006) also found no differences (P > 0.05) in pH values of longissimus steaks from cattle supplemented with or without ZH.
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Initial Color.
Initial color scores were similar (P > 0.05) among ZH feeding durations (Table 4); however, the DSM was a lighter cherry red (P < 0.05, decreased initial color score, 3.2) than the SSM (4.9). Our initial color scores were similar to those of Seyfert et al. (2004), who reported reduced initial color scores for the DSM (3.2) than the SSM (4.8) for HO-MAP-packaged steaks.
Display Color. A significant diet x muscle area x display day interaction occurred for display color scores (Table 5). For the DSM portion, steaks from cattle fed ZH0, ZH20, and ZH40 diets had no differences (P > 0.05) in display color scores on d 0 and 1, increased (P < 0.05) scores on d 2, 3, and 4, but no differences (P > 0.05) in display color between d 4 and 5. The DSM from cattle on the ZH30 did not differ (P > 0.05) in display color scores on d 0 and 1 or d 1 and 2 but darkened (P < 0.05) on d 3 and 4. Display color scores for the DSM from ZH30 cattle were not significantly different on d 4 and 5 of display. No differences (P > 0.05) in display color scores occurred because of dietary regimen for the DSM portion for d 0 through 3. On d 4, the DSM of steaks from the ZH20 and ZH30 diets was brighter red (P < 0.05, decreased display scores) than that of steaks from cattle fed ZH40. On d 5, only the DSM portion of steaks from the ZH20 diet was brighter (P < 0.05) than the DSM from ZH40 fed cattle. No literature was found regarding the effects of β-agonist supplementation on color development and stability of the SM muscle portions.
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In the present study, the DSM and SSM from dietary regimens were still considered acceptable (display color score less than 5.5) by panelists on d 5 of display, whereas the SSM from ZH0, ZH30, and ZH40 cattle diets was borderline unacceptable by the end of display (Table 5).
Discoloration.
Figure 2 shows the diet x display day interaction for discoloration scores. No differences (P > 0.05) in steak discoloration occurred because of ZH feeding duration on d 0, 1, or 2 of display. Steaks from the ZH40 diet regimen had increased (P < 0.05) discoloration scores compared with those from the other dietary regimens on d 3 through 5 of display. By the end of display, steaks from all diet groups were less than 40% discolored. No diet x muscle area interaction was noted for discoloration scores of beef steer steaks (data not shown). Follett et al. (1974) noted a relationship between increased biochemical activity and an increased DSM temperature during chilling that resulted in poor ability to reduce pigment. This could explain the increased rate of DSM discoloration seen in the present study. MacDougall (1982) and Sammel et al. (2002b) also noted that slow chilling of the DSM at greater temperatures than the SSM would denature DSM proteins, resulting in poor reducing capacity.
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also reported decreased (P < 0.05) hue angle values for LM steaks from control cattle compared with those from cattle fed ZH. As expected, all diet regimens had a numerical decrease (P > 0.05) in a*, b*, and saturation index values from d 0 through 5 of display. CO-MAP Steaks
pH. Steaks from the ZH30 cattle diet and packaged in CO-MAP had a reduced (P < 0.05) pH than steaks from other diet regimens (Table 6). The DSM steaks in CO-MAP had a reduced (P < 0.05) pH in the DSM (5.44) than the SSM portion (5.47), although these differences in pH were likely of little practical significance.
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Odor Scores. Odor scores at the end of display were not significantly different for ZH feeding duration (Table 6). All steaks had a small to moderate off-odor at the end of display.
Initial Color.
The DSM of steaks from all diet treatments was a lighter (P < 0.05) cherry red than the SSM (Figure 3). Within muscle areas, DSM and SSM steaks from the ZH20 and ZH30 diets had decreased (P < 0.05) initial color scores than the DSM of control steaks and the SSM of the ZH40 diet, respectively. These data agree with Hunt et al. (2004), who reported numerically less initial color scores for the DSM compared with SSM of steaks exposed to a CO-MAP system.
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and Sørheim et al. (1999) reported a red to bright red color for up to 14 d of display for beef loin steaks packaged in CO-MAP at 4°C. Sirloin steaks packaged in CO-MAP were bright red to reddish tan for 21 d of storage (John et al., 2005). Discoloration. No differences (P > 0.05) in discoloration scores occurred because of diet regimen (Figure 5) until d 8 and 9 of display. On d 8, steaks from the ZH30 feeding duration were less discolored (P < 0.05) than control steaks. By d 9, ZH30 and ZH40 diets had decreased (P < 0.05) discoloration scores than control and ZH20 diets. Overall, CO-MAP steaks from all diet regimens had almost no discoloration until d 9, when diet treatments were slightly more discolored (P < 0.05) than on d 0 through 8 of display.
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reported greater visual color scores (indicative of more discoloration) for HO-MAP-packaged beef loin steaks and pork chops after 10 and 14 d, respectively, compared with steaks and chops in CO-MAP. Instrumental Color. No interactions (P > 0.05) for L* values due to diet regimen and day of display or muscle area were observed (Table 6). However, steaks from the ZH20 and ZH30 feeding regimens were lighter (P < 0.05) than control steaks.
There were no significant interactions or main effect dietary differences for a*, b*, and saturation index values (Table 6). However, a diet x muscle area interaction was significant (Table 3); the DSM of steaks from all dietary treatments was more discolored (P < 0.05, greater hue angles) than the SSM. Within muscle area, no differences (P > 0.05) in hue angles occurred because of diet regimen for the SSM; however, the DSM of the ZH20 diet was more (P < 0.05) discolored than the DSM of steaks from other feeding durations. Hue angle values in our study were comparable with those of John et al. (2005), who reported hue angles for sirloin steaks of 34.1 and 34.0 after 7 and 14 d, respectively, of display in CO-MAP.
Summary
Values for pH of beef steaks packaged in PVC, HO-MAP, and CO-MAP were within an acceptable range and would not negatively affect SM color. There were no practical differences in pH values due to ZH feeding duration, display day, or muscle area.
Only a few significant differences occurred in display and instrumental color of steaks because of ZH feeding duration across packaging types. The PVC-packaged steaks from beef steers fed ZH40 were redder (greater a* values) and more yellow (greater b* values) initially, but color panelists evaluated ZH40 steaks as darker and more discolored in later days of display. Steaks from beef steers fed ZH20 or ZH30 for intermediate durations and packaged in HO-MAP or CO-MAP were slightly brighter red and less discolored during simulated display than control or 40-d steaks. Our data indicate that steaks from ZH20 and ZH30 diets and packaged in PVC or MAP will have an equal or slight advantage in display color stability compared with steaks from nonsupplemented cattle. Feeding ZH40 causes minor detrimental effects on display color and discoloration scores.
More notable than ZH diet differences was the variation in color development and stability of the SM muscle areas. Although the DSM had better initial and display color scores at the beginning of simulated display, it became dark and discolored rapidly after only 1 to 2 d in PVC packaging. Compared with PVC packaging, HO-MAP and CO-MAP improved display and instrumental color differences between the DSM and SSM. Both muscle portions of beef steaks were the brightest red and least discolored at the end of display in CO-MAP. Use of CO-MAP for SM steaks will minimize differences in color between the DSM and SSM.
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Footnotes |
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2 The authors acknowledge Tyson Foods for their support of this research.
3 Corresponding author: hhunt{at}ksu.edu
Received for publication January 28, 2009. Accepted for publication April 28, 2009.
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LITERATURE CITED |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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